Programming Kotlin

When It’s Time to Use when

Kotlin doesn’t have switch; instead it has when, and that comes in different flavors: as expression and as statement.

When as an Expression

Here’s an implementation of the function to determine if a cell will be alive in the next generation in Conway’s Game of Life.^[16]

iteration/boring.kts

fun isAlive(alive: Boolean, numberOfLiveNeighbors: Int): Boolean {
  if (numberOfLiveNeighbors < 2) { return false }
  if (numberOfLiveNeighbors > 3) { return false }
  if (numberOfLiveNeighbors == 3) { return true }
  return alive && numberOfLiveNeighbors == 2
}

This code tells if a cell will live in the next generation, but any programmer reading such code may quickly lose motivation to live; the code ...